Saclay, 30 January 2007Saclay, 30 January 2007Rauno JulinRauno Julin

Department of PhysicsDepartment of PhysicsUniversity of JyväskyläUniversity of Jyväskylä

FinlandFinlandJYFLJYFL

In-beam In-beam Spectroscopy of Spectroscopy of Transfermium NucleiTransfermium Nuclei

Outline:

Introduction

Even-Even254No ( Z =102, N = 152 )250Fm ( Z =100, N = 150 )

Odd-Proton251Md (Z = 101, N = 150)255Lr (Z = 103, N = 152)

Odd-Neutron 253No (Z = 102, N = 151)

Future plans

Spectroscopy of very neutron deficient Spectroscopy of very neutron deficient and heavy nuclei at JYFLand heavy nuclei at JYFL

Can be produced via fusion evaporation with stable-ion beams and stable targets Can be produced via fusion evaporation with stable-ion beams and stable targets

Short-living alpha or proton emitters → tagging methodsShort-living alpha or proton emitters → tagging methods Cross-sections down to 1 nbCross-sections down to 1 nb

Only levels near the yrast line populatedOnly levels near the yrast line populated

Recoil – Decay –Tagging (RDT) method

JUROGAM 43 Ge + BGO Eff. 4%

RITUGas-filled recoil

separator

Transmission 20-50 %

GREATFocal plane spectrometer

TDRTotal Data ReadoutTriggerless data acquisition systemwith 10 ns time stamping+ GRAIN the Analyser

RDT Instrumentation at JYFL

prompt e -

SACRED electron spectrometer at the RITU target

Transfermium NucleiProduced in asymmetric cold-fusion reaction – X(48Ca,2n)Y → ideal for the gas-filled separator RITU→ Only one reaction channel open→ Total compound cross-section down to 50 mb → Ibeam up to 30pnA on a 0.5mg/cm2 target in in-beam runsFission dominates: 100000 : 1→ Ibeam limited by the Ge rate→ Very low focal-plane rate→ Enables long t1/2 – α – tagging

254NoZ = 102, N = 152

254254NoNo

842

943

In-beam γ- rays from 208Pb(48Ca,2n) 254No - 2µbJUROGAM + RITU

S. Eeckhaudt et al. EPJ A26, (2005), 227

0

250

500

750

1000

12501500

1750

2000

2250

2500

2750

3000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

I [hbar]

Ele

vel

[keV

]

In-beam γγ coincidences from 254No 254254NoNo

?

254No-recoil gated in-beam conversion electrons from

208Pb(48Ca,2n) 254No

Discrete lines

+

M1 continuum

M1

P.A. Butler at al. PRL 89 (2002) 202501

SACRED + RITU data

254254NoNo

254No Levelscheme

Long isomer

Short isomer

3+

8-

(16+)

55 s

R.-D. Herzberg et al. Nature 442, 896-899 (24 August 2006)

250FmZ = 100, N = 150

Singles Gamma-Ray Spectra from 204Hg(48Ca,2n)250Fm(HgS targets)

A. Pritchard, R.-D. Herzberg et al., University of Liverpool

250Fm electron spectra

250Fm preliminaryPT G

reen

lees, R

DH

et a

l, pre

limin

ary

!

JUROGAMTagged with isomer

250Fm LevelschemePT G

reen

lees, R

DH

et a

l, pre

limin

ary

!

?

?

Kinematic moment of inertia J(1) even – even nuclei

Dynamic moment of inertia J(2)

even – even nuclei

0,05 0,10 0,15 0,20 0,25

60

70

80

90

100

110

120

130

140

254No

252No

250Fm

I(2) [h

2 /MeV

]

Rotational frequency [MeV]

Dynamic moment of inertia

even – even nuclei

250Fm Dynamic Moment of Inertia J(2)

Theory:

M. Bender et al., NPA 723 (2003) 354

♦ Exp

A Afanasiev, priv comm.

250Fm Kinematic and Dynamic Moment of Inertia J(1) and J(2)

A. Afanasiev, PRC 67, 24309, (2002)

Kinematic and Dynamic Moments of Inertia J(1) and J(2)

Odd - proton 251Md150 , 255Lr152

[521]1/2-

[514]7/2-

[633]7/2+

Electromagnetic Properties

• Odd-proton orbitals in 251Md / 255Lr• B(M1)/B(E2) depends on (gK-gR)/Q0

gK ~ 0.7 Mainly E2[514] 7-

2

7 -

2

7 +

2

[633] 7+

2gK ~ 1.3 Mainly M1

1 -

2

[521] 1-

2a ~ 0.9:

gK ~ -0.55

Mainly E2

Conversion coefficients Z ≈102

Prompt γ-ray spectroscopy of 251Md and 255Lr

205Tl(48Ca,2n)251Md ~ 760 nb(A. Chatillon, Ch. Theisen et al. )

209Bi(48Ca,2n)255Lr~ 300 nb(S. Ketelhut, P. Greenlees et al.)

Recoil Tagging

γγ coincidences

First rotational band in an odd-Z transfermium

No signature partner : K=1/2 251Md

Dynamical Moments of Inertia J(2)

J (2

) (h

bar

2 MeV

-1)

Rotational Frequency

251Md Dynamic Moment of Inertia J(2)

Theory:

M. Bender et al., NPA 723 (2003) 354

185

200

HFB + SLy4M. Bender et al.

300

430

W.S.S. Ćwiok et al.

½-

7+

2

HFB + GognyH. Goutte, priv. comm.

100

7-2

½- ½-

7-2

7-2

7+

2

7+

2

255Lr – Recoil Tagging209Bi(48Ca,2n)255Lr

255Lr – Recoil Decay Tagging

Comparison 255Lr – 251Md

Odd - neutron 253No151

Confirmed byF.P. Heßberger et al.E.P.J. A 22, 417 (2004)

The ground state of 253No is a neutron 9/2- [734] state

0

25

50

75

100

125

Co

unts

/ke

V

100 200 300 400Ene rg y [ke V]

0

2

4

6

8

10

Co

unts

/5 k

eV

GREAT spectra from 207Pb(48Ca,2n)253No

γ rays

electrons

253253NoNo

1.7 min

EarlierGammasphere+FMA

experiment207Pb(48Ca,2n)253No – 0.5µb

P. Reiter et al. PRL 95, 032501 (2005)

253253 NoNo

253253 NoNo JUROGAM + RITU

Recoil-gated γ rays from 207Pb(48Ca,2n)253No

253

253 NoNo Exp

K=7/2 simulation

K=9/2 simulation

It is not 7/2+[624] band but 9/2-[734]

253No

It is not 7/2+[624] band but 9/2-[734]

253No

253253 NoNo

SACRED + RITU data

In-beam conversion electrons from 207Pb(48Ca,2n) 253No

K=7/2 simulation

K=9/2 simulation

Exp

9/2- [734]Indeed

P. Butler et al.

Dynamic moment of inertia J(2)

Theory:

M. Bender et al., NPA 723 (2003) 354

PERSPECTIVES

Improved sensitivity for in-beam studies:Improved sensitivity for in-beam studies:• Digital signal processing → Higher counting Digital signal processing → Higher counting

raterate

Development of high-intensity beams

In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron spectrometer -

SAGE

PERSPECTIVES

Improved sensitivity for in-beam studies:• Digital signal processing → Higher counting rate

Development of high-intensity beamsDevelopment of high-intensity beams• 5050Ti + Ti + 208208Pb → Pb → 256256Rf + 2n Rf + 2n

In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron spectrometer -

SAGE

In-beam γ rays from 208Pb(50Ti,2n)256Rf – 12nb700 recoils ↔ 25pnA, 1 week

Simulation – a random bit of the 254No experiment

256RfZ = 104

PERSPECTIVES

Improved sensitivity for in-beam studies:• Digital signal processing → Higher counting rate

Development of high-intensity beams

In-beam gamma - electron concidences for SHE: In-beam gamma - electron concidences for SHE: • Combined gamma-ray and electron Combined gamma-ray and electron

spectrometer - SAGEspectrometer - SAGE

SAGESAGEUK investment

SAGESAGE

Collaborating institutes

Thank you for your attention !Thank you for your attention !

Moment of inertia